Dropper post assembly for a bicycle

ABSTRACT

A dropper post assembly for supporting a bicycle seat can include an outer tube and an inner tube telescopically receivable in the outer tube and slidable within the outer tube between a retracted position in which a lower end of the inner tube is proximate a lower end of the outer tube and an extended position in which the lower end of the inner tube is axially spaced from the lower end of the outer tube. An actuator assembly may include an actuator body having a mounting portion connected to the lower end of the outer tube and a cartridge rod receiving portion, and may be configured so that when the inner tube is in the retracted position at least the upper surface of the cartridge rod receiving portion is nested within the inner tube.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Ser. No. 16/908,220which was filed Jun. 22, 2020, which itself was a continuation of U.S.Ser. No. 16/837,722 which was filed Apr. 1, 2020 and which claims thebenefit of and priority to U.S. provisional patent application No.62/830,405 filed on Apr. 6, 2019, and U.S. patent application No.62/839,594 filed on Apr. 26, 2019, the entirety of which are herebyincorporated by reference.

FIELD OF THE INVENTION

In one of its aspects, the present disclosure relates to a bicycle seatpost assembly, and in particular to a dropper post assembly for abicycle and an actuator assembly for controlling the internalspring/mechanism of the dropper seat post.

INTRODUCTION

Adjustable bicycle seat posts can provide a variety of seat heightoptions to riders. To enable riders to adjust the height of their seatpost while riding, so-called “dropper” seat posts have been developed.Dropper seat posts are telescopic posts that allow the rider to changethe height of their seat without having to stop and manually adjust themechanically tightened seat post collar. A typical dropper seat postallows a rider to extend and retract a portion of their seat post whilein motion to provide a high and low seat position, respectively.

Taiwan patent publication no. TW201801969 discloses a casing gap fillingstructure for a bicycle seat tube, which comprises a casing set havingan outer tube and an inner tube which are sleeved onto each other andmove linearly. A rotation constraining set is arranged between the innertube and the outer tube and is provided with a first constraining groovearranged on the inner diameter edge of the outer tube and a secondconstraining groove arranged on an outer diameter edge of the innertube. The first and second constraining grooves form a constrainingspace together, and at least one constraining member made of a metalmaterial is accommodated in the constraining space and capable ofconducting synchronous linear displacement with the inner tube. A gapfiller set is disposed in the constraining space and provided with atleast one constraining member made of a plastic material. The gap fillerset and the metal constraining member respectively overlap with eachother in the constraining space along the axial direction of the innerand outer tubes, and the plastic constraining member fills theconstraining space so as to eliminate the gaps among the plasticconstraining member and the first and second constraining grooves. Inthis way, the rotation constraining set and the gap filler set are usedto achieve the dual function of constraining the rotation andeliminating the gaps between the inner tube and the outer tube at thesame time. The manufacturing cost of the filling structure is lowbecause the overall components are simple and easy to be assembledquickly. Further, the gaps among the components generated by the fittolerance and the manufacturing tolerance are reduced with norequirement of tight rotation actions. The automatic filling function isthus achieved and compatible with the lifting seat tube and thesuspension seat tube.

U.S. Pat. No. 9,688,331 discloses a bicycle seat post assembly, whichincludes first and second tubes that are telescopically arranged, afluid chamber that includes a compressible fluid to generate a force toexpand the first and second tubes relative to each other, and apositioning structure. The positioning structure includes a supportmember on one of the first tube and the second tube, a positioningmember that pivots about an axis between a first position and a secondposition, a control unit, which is connected to the positioning memberto move the positioning member between the first position and the secondposition, and a position maintaining member, which is provided on theother of the first tube and the second tube. The position maintainingmember includes an engaging portion that engages with the positioningmember to maintain a positional relationship between the first andsecond tubes.

U.S. Pat. No. 8,079,772 discloses an adjustable height seat post forbicycles that comprises an inner tube slidably contained within an outertube which supports a bicycle seat. The outer tube clamps into a bicycleframe and contains a spring which acts to force the inner tube upward.The inner tube is allowed longitudinal movement within the fixed outertube via a locking mechanism that forces ball bearings into pockets orchannels on the inner tube. The locking mechanism can be remotelyactivated with a handlebar mounted lever or manually with a seat postmounted lever.

US patent publication no. 2015/0232158 discloses a bicycle seat postassembly that includes a first cylinder, a second cylinder, and apositioning structure. The second cylinder is configured to betelescopically received in the first cylinder. The positioning structureis configured to relatively position the first cylinder and the secondcylinder. The positioning structure is configured to switch a state ofthe bicycle seat post assembly among a first adjustable state and asecond adjustable state. In the first adjustable state, a positionalrelationship between the first cylinder and the second cylinder iscontinuously adjustable within a first adjustable position range. In thesecond adjustable state, the positional relationship between the firstcylinder and the second cylinder is continuously adjustable within asecond adjustable position range different from the first adjustableposition range.

SUMMARY

In recent years, “dropper” seat posts have become more desirable. It isadvantageous to lower a bicycle seat as far as possible when ridingthrough technical terrain to allow the rider to change their bodyposition or bend their knees deeply without contacting the seat.

Shorter riders are often required to use shorter travel dropper posts toreduce the overall length because there is less distance between aninsertion limiting feature of the seat tube and the rails of the bicycleseat when at their preferred seat height. This distance relates to thetotal length of the dropper post.

It is typical for dropper posts to be sold in a variety of travellengths. For example, a manufacturer may offer stock dropper post modelswith travel lengths that vary by 20 mm to 25 mm with each model (e.g.,125 mm travel, 150 mm travel, 170 mm travel, etc.).

Despite the advances made to date in the development of bicycle seatpost assemblies, there is room for improvement to address theabove-mentioned problems and shortcomings of the prior art.

In accordance with one broad aspect of the teachings described herein, adropper post assembly for supporting a bicycle seat may include an outertube extending along a post axis between a lower end and an upper end.An inner tube may be telescopically receivable in the outer tube and mayhave an upper end that is connectable to a bicycle seat and a lower endthat is disposed within the outer tube. The lower end may have a lowerend surface defining a lower plane that is substantially orthogonal tothe post axis and intersects a lowermost portion of the lower endsurface. The inner tube may be axially slidable within the outer tubebetween a retracted position in which the lower end of the inner tube isproximate the lower end of the outer tube and an extended position inwhich the lower end of the inner tube is axially spaced from the lowerend of the outer tube. An actuator assembly may include an actuator bodyhaving a mounting portion connected to the lower end of the outer tube,a cartridge rod receiving portion having a cavity extending axially froman upper surface and configured to receive a cartridge rod containing atranslatable actuation rod, and an actuating mechanism movably connectedto the actuator body and configured to selectably translate theactuation rod when in use. The actuator assembly may be configured sothat when the inner tube is in the retracted position at least the uppersurface of the cartridge rod receiving portion is nested within theinner tube and is above the lower plane.

The actuator body may include an axially extending channel that isconfigured to movably receive the actuating mechanism and is bounded byan upper end wall having a rod aperture that is sized to receive theactuation rod. When the inner tube is in the retracted position theupper end wall and at least a portion of the channel may be disposedwithin the inner tube and above the lower plane.

The actuating mechanism may include an engagement member that is movablewithin the channel and that includes an actuation rod contact surfaceconfigured to bear against a lower end of the actuation rod when in use.While the inner tube is in the retracted position the engagement membermay be movable relative to the actuator body between a lower position inwhich the actuation rod contact surface is below the lower plane and anupper position in which the actuation rod contact surface is within theinner tube, above the upper plane and proximate the upper end wall ofthe channel.

The entire engagement member may be disposed laterally inboard of/withinthe inner tube.

The actuator assembly further may include a tube stop surface upon whichthe lower end surface rests when the inner tube is in the retractedposition, and the upper end wall may be spaced axially above the tubestop surface.

The mounting portion may have a first diameter sized to engage the outertube and an insertable portion of the actuator body may be disposedabove the mounting portion and may have a second smaller diameter and issized to be nested within the inner tube. The insertable portion mayinclude the cartridge rod receiving portion, the upper end wall and atleast a portion of the channel.

The actuator body may have a length in the axial direction between anaxially uppermost and axially lowermost surfaces, and when the innertube is in the retracted position at least 10% of the length of theactuator body may be nested within the inner tube, or when the innertube is in the retracted position at least 20% or at least 30% of thelength of the actuator body may be nested within the inner tube.

The actuator assembly may be separable from the outer tube via a singleoperation when the mounting portion is disconnected from the outer tube.

The mounting portion may include a threaded portion that threadinglyengages corresponding threads on an inner surface of the outer tube. Theactuator assembly may be removable from the outer tube in a singleoperation by unthreading the threaded portion from the outer tube.

The actuator body may be of integrally formed, one-piece construction.

The cavity of the cartridge rod receiving portion may have a laterallyextending lower end wall for abutting a lower end of the cartridge rod.When the inner tube is in the retracted position the lower end wall maybe nested within the inner tube.

When the inner tube is in the retracted position the lower end wall maybe disposed above the lower plane by least about 2 mm.

The dropper post assembly may include a locking spring cartridge havinga cartridge outer tube disposed within and movable with the inner tube,a cartridge rod extending from the cartridge outer tube to a lower endthat is received within the cartridge rod receiving portion of theactuator assembly and an actuation rod translatable within the cartridgerod to trigger the locking spring cartridge. When the inner tube is inthe retracted position the lower end of the cartridge rod may bedisposed within the inner tube and above the lower plane.

The lower end of the cartridge rod may have an end surface that isspaced above the lower plane by about 2 mm when the inner tube is in theretracted position.

The cavity of the cartridge rod receiving portion may extend from theupper surface to a lower end wall that is spaced axially from the uppersurface and comprises an aperture through which the actuation rod istranslatable when in use, and wherein the actuator assembly configuredso that when the inner tube is in the retracted position the lower endwall of the cartridge rod receiving portion is nested within the innertube and is above the lower plane

In accordance with another broad aspect of the teachings describedherein, a dropper post assembly for supporting a bicycle seat mayinclude an outer tube extending along a post axis between a lower endand an upper end. An inner tube may be telescopically receivable in theouter tube and may have an upper end including an upper travel edgedefining an upper plane and a lower end that is disposed within theouter tube and comprising a lower end surface defining a lower plane.The inner tube may be axially slidable within the outer tube between aretracted position in which the lower end of the inner tube is proximatethe lower end of the outer tube and the lower plane is coplanar with aretraction plane, and an extended position in which the lower end of theinner tube is axially spaced from the retraction plane by a drop length,a travel portion of the inner tube is exposed outside the outer tube anda lower portion of the inner tube remains axially overlapped within thelower tube defining an overlap length. A seat clamp assembly may beconnected to the upper end of the inner tube and may include first andsecond clamping channels configured to retain first and second bicycleseat rails when in use. The first and second clamping channels mayextend along respective first and second channel axes that lie in acommon rail plane that intersects the post axis at a head point. Adistance between the head point and the upper plane may define a headlength. An actuator assembly may be at the lower end of the outer tubeand may include an actuator body having an axially uppermost surfacethat is disposed above the retraction plane and an opposing axiallylowermost surface that is spaced below the retraction plane by aneffective actuator length. The actuator assembly may be configured sothat at least the axially uppermost surface is nested within the lowerend of the inner tube and above the lower plane when the inner tube isin the retracted position whereby a sum of the overlap length, the headlength and the effective actuator length defines a normalized postlength that is less than about 160 mm.

The normalized post length may be less than about 140 mm.

The drop length may be between about 150 mm and about 240 mm.

A sum of the overlap length, the head length, the effective actuatorlength and two times the drop length may defines a total post lengththat is between 400 mm and about 585 mm.

The overlap length may be at least 80 mm.

The head length may be less than about 40 mm.

The effective actuator length may be less than 40 mm.

The actuator body may include: a mounting portion connected to the lowerend of the outer tube; a cartridge rod receiving portion configured toreceive a cartridge rod containing the translatable actuation rod; andan actuating mechanism movably connected to the actuator body andconfigured to selectably translate an actuation rod when in use.

The cartridge rod receiving portion may include a cavity extendingaxially from an upper surface. The actuator assembly may be configuredso that when the inner tube is in the retracted position at least theupper surface of the cartridge rod receiving portion is nested withinthe inner tube and is above the lower plane.

The head length may be less than the effective actuator length.

The actuator assembly may be separable from the outer tube via a singleoperation when the mounting portion is disconnected from the outer tube.

The actuator body may have a length in the axial direction between theaxially uppermost and axially lowermost surfaces. When the inner tube isin the retracted position at least 10% of the length of the actuatorbody may be nested within the inner tube.

When the inner tube is in the retracted position at least 20% or atleast 30% of the length of the actuator body may be nested within theinner tube.

In accordance with yet another broad aspect of the teachings describedherein, a dropper post assembly for supporting a bicycle seat mayinclude an outer tube extending along a post axis between a lower endand an upper end. An inner tube may be telescopically receivable in theouter tube and may have an upper end including an upper travel edgedefining an upper plane and a lower end that is disposed within theouter tube and comprising a lower end surface defining a lower plane.The inner tube may be axially slidable within the outer tube between aretracted position in which the lower end of the inner tube is proximatethe lower end of the outer tube and the lower plane is coplanar with aretraction plane, and an extended position in which the lower end of theinner tube is axially spaced from the retraction plane by a drop length,a travel portion of the inner tube is exposed outside the outer tube anda lower portion of the inner tube remains axially overlapped within thelower tube defining an overlap length. A seat clamp assembly may beconnected to the upper end of the inner tube and may include first andsecond clamping channels configured to retain first and second bicycleseat rails when in use. The first and second clamping channels mayextend along respective first and second channel axes that lie in acommon rail plane that intersects the post axis at a head point. Adistance between the head point and the upper plane may define a headlength. An actuator assembly may be at the lower end of the outer tubeand may include an actuator body having an axially uppermost surface andan opposing axially lower most surface that is spaced below theretraction plane by an effective actuator length. The dropper postassembly may be configured so that a sum of the overlap length, the headlength and the effective actuator length defines a normalized postlength that is less than about 140 mm.

The lower end of the inner tube may include a lower end surface definingan lower plane and wherein the axially upper most surface of theactuator body is disposed above the retraction plane and the actuatorbody may be configured so that at least the axially uppermost surface isnested within the lower end of the inner tube and above the lower planewhen the inner tube is in the retracted position.

The actuator body may also include: a mounting portion connected to thelower end of the outer tube; a cartridge rod receiving portionconfigured to receive a cartridge rod containing the translatableactuation rod; and an actuating mechanism movably connected to theactuator body and configured to selectably translate an actuation rodwhen in use.

The cartridge rod receiving portion may include a cavity extendingaxially from an upper surface. The actuator assembly may be configuredso that when the inner tube is in the retracted position at least theupper surface of the cartridge rod receiving portion is nested withinthe inner tube and is above the lower plane.

The normalized post length may be less than about 140 mm.

The drop length may be between about 150 mm and about 240 mm.

W sum of the overlap length, the head length, the effective actuatorlength and two times the drop length defines a total post length thatmay be between 400 mm and about 585 mm.

The overlap length may be at least 80 mm.

The head length may be less than about 40 mm

The effective actuator length may be less than 40 mm.

The actuator body may have a length in the axial direction between theaxially uppermost and axially lowermost surfaces. When the inner tube isin the retracted position at least 10% of the length of the actuatorbody may be nested within the inner tube.

When the inner tube is in the retracted position at least 20% or atleast 30% of the length of the actuator body may be nested within theinner tube.

The actuator assembly may be separable from the outer tube via a singleoperation when the mounting portion is disconnected from the outer tube.

The mounting portion may include a threaded portion that threadinglyengages corresponding threads on an inner surface of the outer tube. Theactuator assembly may be separable from the outer tube in a singleoperation by unthreading the threaded portion from the outer tube.

Thus, the present inventors have developed a dropper post assemblyhaving a relatively shorter normalized post length, and a new design foran actuator assembly that can help facilitate the desired arrangementbetween the actuator and inner tube while the dropper post assembly isin use. This may help provide a dropper post assembly with a smalleroverall length which may allow a dropper post to be used in variety ofdifferently configured bicycle frames. This may also help provide adropper post assembly having a desired amount of travel/drop whilerequiring less space/length than a conventional dropper post when in theretracted position and/or while still providing a post with a desireddegree of stability in the extended position. This may help riders tobetter customize the maximum available drop of their seat post to theirheight, bicycle frame size, and/or saddle height requirements. To theknowledge of the inventors, a dropper post assembly with such acombination of features is heretofore unknown. Other advantages maybecome apparent to those of skill in the art upon reviewing the presentdescription.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be described with reference tothe accompanying drawings, wherein like reference numerals denote likeparts, and in which:

FIG. 1 is a side view of one example of a dropper post assembly in aretracted configuration;

FIG. 2 is the dropper post assembly of FIG. 1 in an extendedconfiguration;

FIG. 3 is a partial cross-sectional view of the dropper post assembly ofFIG. 2;

FIG. 4 is a partially exploded view of the dropper post assembly of FIG.1;

FIG. 5 is a partial cross-sectional view of the dropper post assembly ofFIG. 1;

FIG. 6 is a partial cross-sectional view of the dropper post assembly ofFIG. 2;

FIG. 7 is a upper perspective view of one example of an actuatorassembly;

FIG. 8 is a lower perspective view of the actuator assembly of FIG. 7;

FIG. 9 is an enlarged view of a lower portion of a dropper post assemblyincluding the actuator assembly of FIG. 7 in a first state;

FIG. 10 is an enlarged view of a lower portion of a dropper postassembly including the actuator assembly of FIG. 7 in a second state;

FIG. 11 is a upper perspective view of another example of an actuatorassembly;

FIG. 12 is a lower perspective view of the actuator assembly of FIG. 11;

FIG. 13 is an enlarged view of a lower portion of a dropper postassembly including the actuator assembly of FIG. 11 in a first state;and

FIG. 14 is an enlarged view of a lower portion of a dropper postassembly including the actuator assembly of FIG. 11 in a second.

DETAILED DESCRIPTION

Various apparatuses or processes will be described below to provide anexample of an embodiment of each claimed invention. No embodimentdescribed below limits any claimed invention and any claimed inventionmay cover processes or apparatuses that differ from those describedbelow. The claimed inventions are not limited to apparatuses orprocesses having all of the features of any one apparatus or processdescribed below or to features common to multiple or all of theapparatuses described below. It is possible that an apparatus or processdescribed below is not an embodiment of any claimed invention. Anyinvention disclosed in an apparatus or process described below that isnot claimed in this document may be the subject matter of anotherprotective instrument, for example, a continuing patent application, andthe applicants, inventors or owners do not intend to abandon, disclaim,or dedicate to the public any such invention by its disclosure in thisdocument.

Bicycle dropper seat posts allow a rider to change the height of theirseat while riding without having to stop and adjust a mechanicallytightened seat post collar. Dropper seat posts are available indifferent sizes, having different lengths of travel/drop and differentminimum and maximum seat heights. It may be generally desirable toprovide a relative high travel/drop length while still having a dropperpost assembly that feels stable and comfortable to a rider and that canfit within the space available within the bicycle frame. This can berelated to the total length of the dropper post assembly in its extendedand retracted positions, and can be understood to be the sum of theupper and lower travel/drop distances (i.e., the vertical traveldistance of the post), along with an overlap length (i.e., the length ofthe inner tube that remains nested within the outer tube when in itsextended configuration to help provide stability), a head length (i.e.,the distance from the top of the seat tube to the position of the seatrails when mounted to the seat attachment assembly) and an effectiveactuator length (e.g a length by which portions of the actuator extendaxially beyond the lower surface of the inner tube). Together, theselengths can define a total length of the dropper post assembly.

When retracted, the inner tube can be substantially nested within theouter/lower tube but the head length, overlap length and effectiveactuator length remain unchanged (i.e. are nor reduced or nested, etc.when the post is retracted). Therefore, the sum of these generally fixedlengths (the head length, the effective actuator length and the overlaplength) can define a normalized post length that can, in some examples,represent a limit on how low the bicycle seat can be positioned using agiven dropper post assembly while still providing the desired degree oftravel. Reducing this normalized post length may help accommodate awider variety of different riders using a given dropper post.

Shortening or reducing the normalized post length may be done byshortening one or more of the head length, overlap length and theeffective actuator length. One way of shortening the head length is touse a suitable attachment assembly, such as, for example, the seatattachment assembly made and sold by OneUp Components of BritishColumbia, Canada and as described in U.S. Pat. Nos. 10,370,051 and10,583,882 the teachings of which are incorporated herein by reference.Another option is to shorten the degree of overlap between the inner andouter tubes when in the extended position, there by shortening theoverlap length. However, reducing the overlap length can reduce thestability of the inner tube and allow more tilting of the inner postwhile in use. This may reduce rider comfort and/or safety, and/or maycontribute to wear of the dropper post assembly. Preferably, thenormalized post length can be reduced while maintaining a desirableoverlap length.

In conventional dropper post designs a relatively significant amount ofthe overall length comes from the portions of the dropper actuatorassembly that extend below the lower end of the outer tube. The actuatorassembly includes mechanisms that can be triggered, either manually orthrough a remote mechanism like a cable or hydraulic connection, toactivate an internal cartridge or other biasing mechanism that can causethe desired movement of the inner tube. In many conventional designs theactuator assembly is connected to the bottom end of the outer tube andextends completely, or least substantially completely below the lowerend of the outer tube. Positioning conventional actuator assembliesfurther within the outer tube may lead to interference between theactuator assembly and the inner tube and/or cartridge apparatus whichcould limit the amount of travel/drop of the post. The teachingsdescribed herein are generally related to a new dropper post assemblythat can provide a desired travel/drop length while having a relativelysmall, and optionally minimized normalized post length, and to animproved actuator assembly that can be used to help reduce the effectiveactuator length (optionally while still having an overall actuatorlength that is comparable to conventional actuator assemblies).

Referring to FIGS. 1-4, one example of a seat post assembly 100 includesan upper or inner tube 110, a lower or outer tube 120, a collar assembly130 (that can include any suitable seals, bushings and the like) anactuator assembly 140 having an actuating mechanism 170 and one exampleof a seat clamp assembly 150. FIG. 1 shows this assembly 100 with theinner tube 110 in its retracted position and FIG. 2 shows the inner tube110 in its extended position.

Any suitable biasing/driving member can be provided inside the assemblyto help move the inner tube 110, and in this example the assembly 100includes a locking spring cartridge 160 (FIG. 4). This locking springcartridge 160 includes a cartridge outer tube 161, an upper connectionportion 162 for attaching cartridge 160 to upper tube 110, a cartridgerod 163, a rod attaching portion 165 which in this example includes alocking groove and a actuation rod 164 that can translate within thecartridge rod 163 to unlock the locking spring cartridge 160 whentriggered by the actuating mechanism 170. For example, when the dropperpost assembly 100 is in use the actuating mechanism 170 may push or pullthe actuation rod 164 to open a valve (not shown) within the cartridge160 or to otherwise unlock the cartridge 160. Once unlocked, relativeaxial movement between the inner tube 110 and the outer tube 120 is alsopossible. When the actuating mechanism 170 is relaxed/disengaged thecartridge 160 can re-lock and relative motion between the inner tube 110and outer tuber 120 can be inhibited. Referring also to FIGS. 9 and 10,in this example the rod end cap 168 of cartridge 160 is also visible inthe section views and is fixedly engaged with cartridge outer tube 161.A lower most surface 166 of the cartridge rod 163 lies in and defines aplane C. Cartridge rod 163 slides axially through rod end cap 168 whencartridge 160 is unlocked. Rod end cap 168 also has a lower end capsurface 169, which lies in defines a plane E.

The cartridge outer tube 161 is shown as a separate housing in thisexample, but in other examples the cartridge outer tube and the uppertube 110 may be integrally formed with each other, and in such instancesthe upper connection portion 162 may not be required. While one exampleof a locking spring cartridge 160 is described for convenience, theimproved actuator assembly and other aspects of the teachings describedherein may be used in combination with other, suitable biasingcartridges or mechanisms.

The outer tube 120 is, in this example, an elongate, hollow tubularmember that extends along a post axis 151 between a lower end 123 and anupper end 125. The upper end 125 as described herein can include anupper end face of the outer tube 120 itself and can also refer to thecollar 130 and other seals, bushings and such features provided towardthe upper end 125 of the outer tube 120 that remain generally fixed withthe outer tube 120 when the inner tube 110 moves. For example, thecollar 130 acts as a cap on the upper end of the outer tube 120. In theillustrated example, the collar 130 has threads that are configured toengage threads on the upper end of the outer tube 120. Unthreading thecollar 130 can allow a user to access interior of the assembly 100 formaintenance and inspection. As shown in FIG. 3, the upper edges of thecollar 130 (or other uppermost, fixed feature) can define a referenceplane 127 that can be considered to define the upper limit of the outertube 120 for the purposes of the discussion herein.

Referring to FIGS. 2 and 3, in this example the inner tube 110 is agenerally, elongate tube having an upper end 170 and an opposing lowerend 171 that are spaced apart from each other in the direction of a postaxis 151.

The lower end 171 has a lower end surface 111 that lies in and helpsdefine a lower plane A that is also substantially orthogonal to the postaxis 151. In the illustrated example the lower end surface 111 issubstantially planar and therefore lies within the orthogonal plane A.In other examples the lower end surface need not be planar or arrangedin the transverse direction as shown. In such examples plane A can bedefined as a plane that is substantially orthogonal to the post axis 151and that intersects the lowermost portion of the lower end surface ofthe inner tube 110 (or structures attached to and movable therewith asdescribed herein). The plane A is intended to represent the elevation ofthe lowermost portion of the movable, inner tube 110 that would be theportion most likely to contact an obstruction or object that was locatedwithin the outer tube 120 and in the travel path of the inner tube 110.That is, the plane A can still be applied to structures and used as areference point as described herein even when an embodiment of theassembly 100 has variations in the shape and configuration of the lowerend of the inner tube 110. An axial distance between the upper plane 174and lower plane A can define an inner post length that can be betweenabout 175 mm and about 330 mm. The inner post length remains fixed whilethe dropper post assembly 100 is in use.

While the lower end 171 of the inner tube 110 is shown as simply beingan integral part of the tube 110 it may alternatively, in otherembodiments, include some additional pieces or members that can beattached to the tube and may have slightly different shapes orconfigurations—but which are attached to and move with the inner tube110 as it moves between extended and retracted positions. For thepurposes of the discussion herein, the plane A is intended to representthe plane containing the lower most, movable portion of the assembly 100that translates with the inner tube 110 and would be likely to contactor interfere with objects positioned within the lower end of the outertube 120. That is, while lower end surface 111 is shown as being aportion of the tube itself in this example, in other examples the lowerend surface 111 may be provided by the lowermost portion of any suchattachment or other member connected to the inner tube 110 andreferences to the lower end surface 111 and plane A are intended tocover such arrangements.

The upper end 170 of the inner tube 110 can, like the upper end of theouter tube 120, include a variety of structures or other members (inaddition to just a length of tube) such as attachment apparatus forconnecting to and supporting the seat clamp assembly 150. Some of thesefeatures may extend into the or beyond the upper end of the inner tube110 and are translatable with the inner tube 110 as it moves. For thepurposes of the discussion herein the portion of the inner tube 110 thattelescopes within the lower tube 120 (e.g. is at or below plane 127 whenthe inner tube 110 is retracted) can be considered to be the travel ordrop portion of the inner tube 110. The upper edge of the travel portionof the inner tube can include an upper travel edge 173 that can be anend surface of the inner tube 110 itself, a location along the edge orsidewall of the inner tube 110 and/or a portion or surface on anothercomponent mounted to the inner tube 110. For the purposes of thediscussion herein, this upper travel edge 173 can be considered to liein and helps define an upper plane 174 that is generally orthogonal tothe post axis 151. When the inner tube 110 is retracted the upper plane174 may be substantially co-planar with plane 127, and when the innertube 110 is extended the upper plane 174 is spaced from the plane 127 bythe drop length 175 (FIG. 3 and described further herein). The upper end170 is also configured to be connected to a suitable seat clamp assembly150.

When the inner tube 110 is in the retracted position (FIGS. 1 and 5) thesidewall of the inner tube 110 is almost entirely received within theouter tube 120 and the lower end surface 111 can reach its lowermost, orfully retracted position, such that further retraction of the inner tube111 is inhibited. In the illustrated example, movement of the inner tube110 is stopped when the lower end surface 111 contacts and bears againsta tube stop surface 146 which is also at the lower end of the outer tube120. The tube stop surface 146 can be any suitable surface and is, inthis example provided by a gasket member that is supported on theactuator assembly 140. Alternatively, the tube stop surface may beintegrally formed with the actuator assembly 140, may be provided aspart of the outer tube 120 or may be provided as a separate member.Optionally, instead of being positioned at the lower end of the outertube 120 to contact the lower end surface 111, other embodiments of thetube stop surface may be provided in other locations within the assembly100 and may contact other portions of the inner tube 110 or othersuitable structure in order to help stop the inward translation of theinner tube 110. That is, the tube stop surface need not contact thelower end surface 111 as shown, and instead may contact another portionof the inner tube 110 (for example, toward the upper end of the innertube).

Regardless of the configuration of the tube stop surface and/or whichportion of the inner tube 110 it contacts, the location of the plane Awhen the inner tube 110 is in its fully retracted defines the positionof a retraction plane F (FIG. 3). That is, when the inner tube 110 isfully retracted, as shown in FIGS. 9 and 10, the plane A and F areco-planar, and when the inner tube 110 is extended as shown in FIG. 3,plane A can be located at the lower end surface 111 and is spaced fromplane F.

When the inner tube 110 is in the extended position (FIGS. 2, 3 and 6)the lower end surface 111 is axially spaced apart from the tube stopsurface 146 by a distance 175 that is the travel/drop length for thedropper post assembly 100. In this position an upper, travel portion ofthe inner tube 110 is exposed above the outer tube 120 by the samedistance 175 (shown as the distance between planes 127 and 174), whichrepresents the change in height of the bicycle seat when the dropperpost assembly 100 is activated. This drop length 175 can vary withdifferently sized/configured examples of the assembly 100, but may bebetween about 80 mm and about 260 mm, between about 110 mm and about and250 mm and preferably may be between about 150 mm and about 240 mm.

To help keep the inner tube 110 stable a lower portion of the inner tube110 remains nested within the lower tube 120 and/or collar 130 (e.g.below plane 127) when the inner tube 110 is extended. This nestedportion of the inner tube 110 defines an overlap length 176 that isshown in this example as being the axial distance between planes A and127 (e.g. the non-exposed portion of the inner tube 110). The overlaplength can vary with differently sized/configured examples of theassembly 100, but may be between at least 60 mm and 120 mm and may bebetween about 70 mm and about 110 mm, and preferably may be at leastabout 80 mm. In general, increasing the overlap length 176 may helpincrease the stability of the inner tube 110 when extended, which mayreduce wear and/or increase rider comfort.

Referring also to FIGS. 7-10 the actuator assembly 140 has an actuatorbody 143 that in this example is formed from two individual parts 143 aand 143 b that are joined together so that when in use with the assembly100 the body behaves as a single piece, and can be attached and detachedfrom the lower tube 120 as a single unit—without having to separateparts 143 a and 143 b. Alternatively, the body 143 may be formed of morethan two parts or may be of integral, one piece construction (asdescribed herein)

The body 143 includes a mounting portion 141 which in this exampleincludes external threads that extend around the perimeter of the body143. The threads of the mounting portion 141 can engage complementarythreads 121 on an inner surface of the outer tube 120. In thisarrangement the actuator assembly 140 is separable from the outer tubevia a single operation (e.g. unthreading) and in one piece (e.g. withoutrequiring disassembly) when the mounting portion 141 is disconnectedfrom the outer tube 120. In other examples, the mounting portion 141 mayinclude any type of apparatus that can engage with a complementaryportion of the outer tube 120 or other suitable member, and may includefasteners, circlips, clips, a press fit, deformation fit or the like.The region of the body 143 that is above the mounting portion 141 has,in this example been configured to provide a shoulder to accommodate andsupport a cushioning member 144 (FIG. 5) which serves as the upwardlyfacing tube stop surface 146. In this arrangement, the tube stop surface146 is removable from the lower tube 120 with the actuator assembly 140.

The actuator body 143 also includes a cartridge rod receiving portion147 that is configured to attach the cartridge rod 163 to the actuatorbody 143. The cartridge rod receiving portion 147 may have anyconfiguration that is suitable for attaching to a given cartridge rod163 that is used in the assembly 100. In this example the cartridge rodreceiving portion 147 includes an axially oriented cavity 182 thatextends from an aperture 183 that is provided in an upper end surface149 of the body portion which, in this example includes the upper mostsurface of the actuator assembly 140. The aperture 183 is sized toaccommodate the end of the cartridge rod 163. The cavity 182 extends toan opposing lower end wall 184 that includes a rod aperture 185, whichis sized to allow the tip of the actuation rod 164 to pass through. Thecartridge rod 163 can be coupled to the actuator body 143 using anysuitable technique, and in this example is secured in place usingfasteners in the form of bolts 145 a and 145 b which, when installed asshown interact with a locking groove 165 that is provided on thecartridge rod 163. Other methods, including threaded connections, pressfit, deformation fit, clips, adhesives and the like may be used in otherexamples.

The actuator assembly 140 also includes the actuating mechanism 170which includes, in this example a slidable plunger 171 having a dynamiccable stop surface 177 and that supports and drives an engagement member172 in the form of a plate having an actuation rod contact surface 178that bears against an opposing contact surface that is provided on thetip of the actuation rod 164. When the plunger 171 is extended, theplate 172 moves downwardly (as illustrated in FIG. 9) and the actuationrod 164 can also move down. This example of the actuator mechanism 170uses a cable and housing arrangement (not shown) to lower the distancebetween static cable stop surface 142 of body portion 143 b and dynamiccable stop surface 177 of plunger 171. Lowering the distance betweencable stops 177 and 142 moves plunger 171 and plate 172 upward.Actuation rod contact surface 178 pushes actuation rod 164 upward,thereby opening the cartridge valve (not shown). FIG. 8 shows actuatormechanism 170 in a relaxed position. FIG. 9 shows actuator mechanismassembly 170 in an actuated position. In this example, the actuation rodcontact surface 178 provides the upper most surface of the actuatingmechanism 170 and defines plane B in FIGS. 9 and 10. A lower mostsurface 186 of the actuator assembly 140 defines a plane G (FIG. 3).

To help accommodate the movement of the actuating mechanism 170 thisexample of the actuator assembly 140 also includes an axially extendingrecess or channel 187 that is configured to receive the actuatingmechanism 170. In this example the channel 187 is bounded by an upperend wall that coincides with the lower end wall 184 and is incommunication with the rod aperture 185.

To help reduce the normalized post length of the assembly 100, theactuator assembly 140 is configured so that at least a portion of theactuator assembly 140 is disposed within the lower end of the outer tube120 and is sized (e.g. has a diameter 187 that is less than in internaldiameter of the inner tube 110) so that it can be nested within theinterior 112 of the inner tube 110 when the inner tube 110 is retractedand the lower end surface 111 is resting on the tube stop surface 146.Other portions, such as the mounting portion 141 can have a different,larger diameter so that they can engage the larger, outer tube 120. Inthis arrangement, the length of the actuator assembly 140 that extendsbelow the tube stop surface 146, and therefore contributes to normalizedpost length is illustrated as the effective actuator length 188 in FIG.3. The actuator body 143 may also define a body length in the axialdirection that is measured between planes D and G.

Increasing the amount of the actuator assembly 140 that can be nestedwithin the inner tube 110 may help reduce the effective actuator length188 (measured from plane F to surface 186), but it may be desirable insome embodiments to have at least some of the actuator assembly 140exposed and extending below the lower end of the outer tube 120 to helpfacilitate connection of the activation cable. Preferably, the actuatorassembly 140 can be configured so that the effective actuator length 188is less than about 50 mm, may be less than about 35 mm and may be lessthan about 30 mm, less than about 25 mm and/or less than about 20 mm mm.

To help provide the desired nesting, the actuator assembly 140 isconfigured so that the portions provided above the mounting portion 141and tube stop surface 146 are sized to fit within the inner diameter ofthe inner tube 110. Preferably, at least the upper end surface 149 andend wall of the cartridge receiving portion 147 can be nested within theinner tube 110 and located above the lower plane A when the inner tube110 is retracted. Optionally, the actuator assembly 140 can beconfigured so that at least 10%, at least 20%, at least 30%, at least40%, at least 50% or more of the actuator body length can be nestedwithin the inner tube 110 when it is retracted. For example, optionally,the entire cartridge rod receiving portion 147 can be nested within theinner tube 110 and located above the lower plane A when the inner tube110 is retracted, including the end wall 184 and rod aperture 185 alongwith portions of the channel 187 (while a lower portion of the channelextends below plane A). The lower end wall 184, and the lower endsurface 166 of the cartridge rod 163 may be positioned so that it isabove the lower plane A by at least about 1 mm, about 2 mm, about 3 mm,about 5 mm or more when the inner tube 110 is retracted.

When the inner tube 110 is in its retracted position in this example, asshown in FIGS. 9 and 10, entire cartridge rod receiving portion 147along with the lower end of the cartridge rod 163 and actuation rod 164are all nested within the inner tube 110 and above plane A when theinner tube 110 is retracted. In this arrangement, as shown, planes C, D,and E are all disposed above plane A when in the retracted position.

Whether plane B and the plate 172 are disposed above plane A can dependon the state of the actuating mechanism 170. In this example when theactuating mechanism 170 is in the relaxed position of FIG. 8 the plate172 is outside the inner tube 110 and plane B is below plane A. Thisexample of the actuator assembly 140 allows the actuating mechanism 170changed from its relaxed position to its actuated position of FIG. 10with the inner tube 110 retracted, thereby moving both plate 172 andplane B above plane A. In this example the channel 187 and theengagement member 172 are sized so that they are disposed laterallyinboard of the inner tube (i.e. within a projection of thecross-sectional area of the inner tube 110) which can help facilitatethe desired movement of the engagement member 172 independent of theposition of the inner tube 110.

Referring again to FIGS. 3 and 4, the seat clamp assembly 150 in thisexample includes a pair of clamping channels 190 that each extend alongrespective channel axis 191. The channels 190 are sized to receive theseat rails of a standard bicycle seat, with the channel axes 191 beingaligned with the seat rails when installed. The axes 191 are parallel toeach other and lie in a common rail plane 192 (FIG. 3). The rail plane192 may be inclined relative to the post axis 151 and will intersect thepost axis 151 at a head point 193. The axial distance between the headpoint 193 and the plane 174 defines a head length 194, that can be lessthan about 50 mm, less than about 40 mm, less than about 30 mm or lessthan about 25 mm, and may be about 24 mm. Like the overlap length 176and effective actuator length 188, the head length 194 remains fixedwhile the assembly 100 is in use and contributes to the normalized postlength of the assembly 100. The head length 194 is, in this example,less than the effective actuator length 188 and overlap length 176.

Preferably, the assembly 100 is configured, such as by configuring theseat clamp assembly to reduce the head length 194, configuring theactuator assembly 140 to reduce the effective actuator length 188 and/ormodifying the overlap length 176, so that normalized post length is lessthan about 160 mm, and preferably is less than about 150 mm, about 140mm, about 130 mm, about 120 mm, about 110 mm or less. Preferably, thisreduction in the normalized post length can be achieved while stillproviding a standard sized post assembly and providing a drop/travellength that is preferably at least 90 mm, at least 120 mm, at least 150mm, at least 180 mm, at least 210 mm, at least 240 mm or more. This mayprovide an assembly in which a sum of the overlap length, the headlength, the effective actuator length and two times the drop lengthdefines a total post length that is between 300 mm or about 400 mm andabout 585 mm, while still having a relatively small normalized postlength of less than about 160 mm or less than about 140 mm.

Referring now to FIGS. 11-14, another example of an actuator assembly240 that is useable with the dropper post assembly 100 is shown. Theactuator assembly 240 is generally analogous to actuator assembly 240and like features are annotated using like reference characters indexedby 200. In this example the actuator assembly 240 has a body portion243, a cartridge rod receiving portion 247 for receiving the cartridgerod 263. The rod 263 is fastened to the body portion 243 via a threadedconnection 245 (instead of bolts 145 a, 145 b). A tube stop surface 246is provided next to the mounting portion 241. The rod end cap 268 ofcartridge is also visible and is fixedly engaged with cartridge outertube. Rod 263 slides axially through rod end cap 268 when cartridge isunlocked. Rod end cap 268 also has a lower end cap surface 269.

The actuator assembly 240 has an actuator body 243 that in this exampleis of integrally formed, one-piece construction. The body 243 includes amounting portion 241 which in this example is configured to be engagedand retained using a circlip, rather than including a threadedconnection. In this arrangement the actuator assembly 240 is separablefrom the outer tube via a single operation (e.g. removing the circlip)and in one piece (e.g. without requiring disassembly) when the mountingportion 241 is disconnected from the outer tube. The region of the body243 that is above the mounting portion 241 has, in this example beenconfigured to provide a shoulder to accommodate and support a cushioningmember which serves as the upwardly facing tube stop surface 246. Inthis arrangement, the tube stop surface 246 is removable from the lowertube with the actuator assembly 240.

The actuator body 243 also includes a cartridge rod receiving portion247 that is configured to attach the cartridge rod 263 to the actuatorbody 243. In this example the cartridge rod receiving portion 247includes an axially oriented cavity 282 that extends from an aperture283 that is provided in an upper end surface 249 of the body portionwhich, in this example includes the upper most surface of the actuatorassembly 240. The aperture 283 is sized to accommodate the end of thecartridge rod 263. The cavity 282 extends to an opposing lower end wall284 that includes a rod aperture 285, which is sized to allow the tip ofthe actuation rod 264 to pass through. The cartridge rod 263 is threadedinto the cavity 282.

The actuator assembly 240 also includes the actuating mechanism whichincludes a lower arm 271 with dynamic cable stop surface 277, anengagement member 272 in the form of the upper arm that includes theactuation rod contact surface 278, pivot pins 273 and 274 and alignmentpin 275. Actuator mechanism uses a cable and housing arrangement (notshown) to lower the distance between static cable stop surface 242 ofbody 243 and dynamic cable stop surface 277 of lower arm 271. Loweringthe distance between cable stops 277 and 242 pivots lower arm 271 aboutpin 273 thereby pushing upper arm 272 upward while it pivots about pin274. Upper arm 272 is aligned to body 243 by alignment pin 275.Actuation rod contact surface 278 pushes actuation rod 264 upward,thereby opening the cartridge valve (not shown). FIG. 13 shows actuatormechanism assembly in a relaxed position. FIG. 14 shows actuatormechanism in an actuated position. Like actuator mechanism 170, theengagement member 272 can be operated while the inner tube 110 isretracted, such that the plane B may be above or below plane A dependingon the state of the actuator. In this example the channel 287 andengagement member 272 are laterally inboard the inner tube 110.

To help accommodate the movement of the actuating mechanism this exampleof the actuator assembly 240 also includes an axially extending recessor channel 287 that is configured to receive the actuating mechanism. Inthis example the channel 287 is bounded by an upper end wall thatcoincides with the lower end wall 284 and is in communication with therod aperture 285.

To help reduce the normalized post length of the assembly 100, theactuator assembly 240 is configured so that at least a portion of theactuator assembly 240 is disposed within the lower end of the outer tube120 and is sized so that it can be nested within the interior of theinner tube 110 when the inner tube 110 is retracted and the lower endsurface 111 is resting on the tube stop surface 246. Other portions,such as the mounting portion 241 can have a different, larger diameterso that they can engage the larger, outer tube 120. In this arrangement,the length of the actuator assembly 240 that extends below the tube stopsurface 246, and therefore contributes to normalized post length isillustrated as the effective actuator length. The actuator body 243 mayalso define a body length in the axial direction that is measuredbetween planes D and G.

When the inner tube 110 is in its retracted position in his example, asshown in FIGS. 13 and 14, entire cartridge rod receiving portion 247along with the lower end of the cartridge rod 263 and actuation rod 264are all nested within the inner tube 110 and above plane A when theinner tube 110 is retracted. In this arrangement, as shown, planes C, D,and E are all disposed above plane A when in the retracted position.

While this invention has been described with reference to illustrativeembodiments and examples, the description is not intended to beconstrued in a limiting sense. Thus, various modifications of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thisdescription. It is therefore contemplated that the appended claims willcover any such modifications or embodiments.

All publications, patents and patent applications referred to herein areincorporated by reference in their entirety to the same extent as ifeach individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by referencein its entirety.

I claim:
 1. A dropper post assembly for supporting a bicycle seat, thedropper post assembly comprising: a. an outer tube extending along apost axis between a lower end and an upper end; b. an inner tubetelescopically receivable in the outer tube and having an upper endcomprising an upper travel edge defining an upper plane and a lower endthat is disposed within the outer tube and comprising a lower endsurface defining a lower plane, the inner tube being axially slidablewithin the outer tube between a retracted position in which the lowerend of the inner tube is proximate the lower end of the outer tube andthe lower plane is coplanar with a retraction plane, and an extendedposition in which the lower end of the inner tube is axially spaced fromthe retraction plane by a drop length (DL), a travel portion of theinner tube is exposed outside the outer tube and a lower portion of theinner tube remains axially overlapped within the lower tube defining anoverlap length; c. a locking spring cartridge disposed at leastpartially within the inner tube and configured so that when the lockingspring cartridge is locked relative axial movement between the outertube and inner tube is inhibited, and when the locking spring cartridgeis unlocked the inner tube is axially movable relative to the outertube, and comprising an actuation rod that is translatable to unlock thelocking spring cartridge; d. a seat clamp assembly connected to theupper end of the inner tube and comprising first and second clampingchannels configured to retain first and second bicycle seat rails whenin use, the first and second clamping channels extending alongrespective first and second channel axes that lie in a common rail planethat intersects the post axis at a head point, and wherein an distancebetween the head point and the upper plane defines a head length; and e.an actuator assembly at the lower end of the outer tube, the actuatorassembly comprising an actuator body having a mounting portionconnectable to the outer tube, an axially uppermost surface and anopposing axially lower most surface that is spaced below the retractionplane by an effective actuator length, and an actuating mechanism thatis configured to translate the actuation rod; and wherein the dropperpost assembly is configured so that a sum of the overlap length, thehead length and the effective actuator length defines a normalized postlength (NPL) that is less than about 160 mm and wherein the ratio ofnormalized post length to drop length (NPL/DL) is less than about 78%.2. The dropper post assembly of claim 1, wherein the normalized postlength is less than or equal to about 140 mm.
 3. The dropper postassembly of claim 1, wherein the ratio of normalized post length to droplength (NPL/DL) is less than about 67%.
 4. The dropper post assembly ofclaim 3, wherein the ratio of normalized post length to drop length(NPL/DL) is less than about 60%.
 5. The dropper post assembly of claim1, wherein the locking spring cartridge has a cartridge outer tubedisposed within and movable with the inner tube and a cartridge rodextending from the cartridge outer tube to a lower end that is receivedwithin a cartridge rod receiving portion of the actuator assembly,wherein the actuation rod is translatable within the cartridge rod tounlock the locking spring cartridge, and wherein when the inner tube isin the retracted position the lower end of the cartridge rod is disposedwithin the inner tube and above the lower plane.
 6. The dropper postassembly of claim 1, wherein the normalized post length is or is lessthan about 140 mm and wherein the overlap length is at least 70 mm. 7.The dropper post assembly of claim 1, wherein the drop length is betweenabout 150 mm and about 240 mm.
 8. The dropper post assembly of claim 1,wherein the effective actuator length is less than 40 mm.
 9. The dropperpost assembly of claim 1, wherein a sum of the overlap length, the headlength, the effective actuator length and two times the drop lengthdefines a total post length that is between 400 mm and about 630 mm. 10.The dropper post of claim 1, wherein the actuator assembly is separablefrom the outer tube via a single operation when the mounting portion isdisconnected from the outer tube.
 11. The dropper post of claim 1,wherein the locking spring cartridge has a cartridge outer tube that isintegrally formed with the inner tube and a cartridge rod extending fromthe cartridge outer tube to a lower end that is received within acartridge rod receiving portion of the actuator assembly, wherein theactuation rod is translatable within the cartridge rod to unlock thelocking spring cartridge.
 12. A dropper post assembly for supporting abicycle seat, the dropper post assembly comprising: a. an outer tubeextending along a post axis between a lower end and an upper end; b. aninner tube telescopically receivable in the outer tube and having anupper end comprising an upper travel edge defining an upper plane and alower end that is disposed within the outer tube and comprising a lowerend surface defining a lower plane, the inner tube being axiallyslidable within the outer tube between a retracted position in which thelower end of the inner tube is proximate the lower end of the outer tubeand the lower plane is coplanar with a retraction plane, and an extendedposition in which the lower end of the inner tube is axially spaced fromthe retraction plane by a drop length (DL), a travel portion of theinner tube is exposed outside the outer tube and a lower portion of theinner tube remains axially overlapped within the lower tube defining anoverlap length; c. a seat clamp assembly connected to the upper end ofthe inner tube and comprising first and second clamping channelsconfigured to retain first and second bicycle seat rails when in use,the first and second clamping channels extending along respective firstand second channel axes that lie in a common rail plane that intersectsthe post axis at a head point, and wherein an distance between the headpoint and the upper plane defines a head length; and d. an actuatorassembly at the lower end of the outer tube, the actuator assemblycomprising an actuator body having a mounting portion connectable to theouter tube, an axially uppermost surface and an opposing axially lowermost surface that is spaced below the retraction plane by an effectiveactuator length, the dropper post assembly being configured so that asum of the overlap length, the head length and the effective actuatorlength defines a normalized post length (NPL) that is less than about160 mm and wherein the ratio of normalized post length to drop length(NPL/DL) is less than 68%.
 13. The dropper post assembly of claim 12,wherein the normalized post length is less than or equal to about 120mm.
 14. The dropper post assembly of claim 12, wherein the normalizedpost length is less than about 140 mm and wherein the overlap length isat least 80 mm.
 15. The dropper post assembly of claim 12, wherein thedrop length is between about 150 mm and about 240 mm.
 16. The dropperpost assembly of claim 12, wherein the effective actuator length is lessthan 40 mm.
 17. The dropper post assembly of claim 12, wherein a sum ofthe overlap length, the head length, the effective actuator length andtwo times the drop length defines a total post length that is between400 mm and about 630 mm.
 18. The dropper post of claim 12, wherein theactuator assembly is separable from the outer tube via a singleoperation when the mounting portion is disconnected from the outer tube.19. The dropper post of claim 12, wherein the ratio of normalized postlength to drop length (NPL/DL) is less than about 65%.
 20. The dropperpost assembly of claim 19, wherein the ratio of normalized post lengthto drop length (NPL/DL) is less than about 60%.
 21. The dropper postassembly of claim 20, wherein the ratio of normalized post length todrop length (NPL/DL) is less than about 58%.